I wasn’t expecting to learn much about fitness from a woman who’s nearly 50, even if that woman is tennis champ Martina Navratilova. And as a relatively young male (37), the last thing I anticipated was feeling jealous, but that’s what happened.

After six years of aches and pains every morning, I’ve forgotten what it feels like to wake up feeling refreshed. Until I stretch and have a hot, muscle-relaxing shower, I’m useless and grumpy. In my daily life, I walk a lot, practice yoga, and eat very few processed foods, but I do it all with rickety bones and somehow still have a chronic energy deficit.